Personally I find the MD picks up where the potato ends pretty well for me. Unless the waves are gutless it works in anything chest high and up. It's very reliable and holds in well when the waves are solid, fast and steep too.
I personally would prefer more rocker, especially in the tail, for laying into turns on a vertical face. It feels a little stiff to me. I think I might go back to surfing it as a quad actually.

No experience with the Unibrow here either but it's one of the few models that I haven't wanted to run out and buy based on pics and descriptions. I'm pretty sure it won't work that well for me based on the boards I like.
The Jacknife is starting to catch my attention though...

Where"s the Hellfire fall Buzzy, what would say is the max wave height and how does it handle hollow waves?

ridden at the right volume..(lowish/shortish).. the HF has few limits...it rides as a full hi-perf, not like a hybrid..(again, if not ridden too big)... i rode the 510 EVERY day for 12 months at 90+kgs in 1 foot up to scary slabs..(ok the slabs were pushing it but it still rode them with as much attack as a knifey performance board..)..

i hate barrels as i dont want my dodgy back compressed (just ask Goanna or Megsy about my lobster dive bail outs..!!)..and cant twist around safely when bent over so cant drive through anything smaller than standup tubes, but have had a memorable tuck in session on a local bare rock barrel(for boogies most of the time).. HF air drops down, bites its rail off the bottom and drives up into them, then hold speed in there with little input from me...relaxing barrel surfing...and being shorter it fit in easily..